Bob replies...

Hi Robb,

The best phosphate removing product that I know of is a product called ROWAphos. It comes from Germany, however, is now available here - www.aquatichouse.com. The product is a ferric hydroxide material (iron-based product). It differs from other similar material sold here in the U.S. as it is specifically treated in a patented process to increase its absorbability. I would venture a guess its about 40% better than the U.S. brands. Anyway, it's a must in my opinion it be used correctly or you're wasting money, i.e., in a canister filter. I suggest a Fluval 304 for you, which has three internal baskets. Fill the lower basket with your choice of activated carbon (I use the ESV brand - really the best out there!) in a sack of course, and also cut up a Poly-Filter into small pieces. That fills the first basket. In the middle basket place a layer of filter fluff and spread five tablespoons of ROWAphos over the filter fluff. Cover the media with another shallow layer of filter fluff. Do the same in the top basket. Change the media when there is the first sign of any phosphate reading on your test kit. Suggest you use only the Salifert phosphate test kit. If for some reason you can't get the ROWAphos, you can use either the Two Little Fishes or Marc Weiss media, however, increase the amount used. As for Salifert phosphate product, I don't have any details about it, however, would venture a guess it's the same stuff as the Two Little Fishies and Marc Weiss products, as existing contracts in Germany forbid the ROWAphos product being sold to anyone except the one company that now distributes ROWAphos.

As for the products made by Korallin PO4-Minus phosphate, or AZ-NO3 nitrate exporter, it would be a cold day in you know where before I would use them! And I should note I've seen some horror stories where AZ-NO3 is concerned!

And yes, the majority of phosphates comes from the foods fed, especially green foods such as nori and flake foods. But, with proper attention to removal, it should never become a problem. And remember, cyano is a photosynthetic creature, and mostly prefers to be where there is some light penetration, preferably a red spectrum.

As for cyano, I have recently seen a product called Chemi-Clean from Boyd Enterprises used in a store reef tank and it was 100% successful in wiping out a bad case of cyanobacteria, and I mean real bad case! However, when I questioned Boyd about its ingredients, they refused to speak to me! Could be I guessed too closely as to what it was and they didn't like to hear that! I'm guessing it's a concentrated carbohydrate such as a special sweetener that causes the cyano to work overtime and devour itself! I've heard of people using excessive doses of the Marc Weiss Reef-Vital DNA, a similar sweetener product, and all cyano disappearing.

Of course, you could use a tablespoon of brown sugar or unprocessed honey once per month in your 120 gallon tank and it might do the same thing.

Hope this is helpful and have a safe new year.

Bob

Bob replies...

Hi Robb,

The situation around deep and shallow sandbeds directly on the aquarium bottom, plenum systems, nitrate accumulation, and unwanted algae continue to be interesting topics, and often frustrating to say the least.

As with anything, it's better to begin at the root level and work our way towards the end result. That begins, in my opinion, with the aquariums smallest members, its bacteria and the confusion that revolves around the words anoxic and anaerobic.

Depending upon the oxygen level in the sandbed, certain types of bacteria exist. In the first half inch of sand, the aerobic heterotrophs exist and in this oxygen rich area the nitrification cycle is accomplished. Below that and in areas where there is a small amount of oxygen (0.5 - 2.0 mg/l), facultative anaerobic heterotrophs exist. It past research we have termed that area as 'anoxic.' Those bacteria living in that area are capable of reducing nitrate back to nitrogen gas. In a system without a plenum, that area would be approximately the lower half of the upper inch of substrate. Of course the physical grain size of the medium is important, but for all practicable purpose I'm assuming something in the range of 1 - 4 mm. Where there is no oxygen, such as below one inch in depth, obligate anaerobic heterotrophs exist and they only reduce nitrate to ammonium, no further. Basically the same is true for what is happening inside live rock. So, the production of a nitrogen based product, ammonium, is occurring where there is no oxygen. We call that the anaerobic area.

The ammonium produced in an anaerobic area, if it leaches upwards, either gets used by algae, as ammonium is the prime algae nutrient, or it has to be converted by nitrification bacteria back to nitrate. So the nitrification bacteria in the upper half inch of the bed are working overtime in trying to keep pace with the incoming supply of nutrients in both directions. If some of the nitrates and ammonium leach back into the bulk water, O'well, there's just so many nitrification aerobic bacteria and they are all already doing the best they can!

The claim that an anaerobic region in the sandbed is something good to create because it reduces nitrates is a weak and misleading statement! A more potent nutrient, ammonium, is being produced!

If the depth of the bed directly on the aquarium bottom is reduced to a couple of inches, there is simply less anaerobic/inefficient area. If the bed is much deeper, the penetration of oxygen via diffusion is hampered, thereby reducing the level of very efficient nitrate reduction, i.e., back to nitrogen gas. Therefore the deeper region of a sandbed directly on the aquarium bottom can become an endless cycling factory of ammonium to nitrate and back to ammonium. Of course there are other considerations, such as bioturbation/influx of fauna, however, that's usually a wildcard and its associated value impossible to quantify. So it's a must I dwell upon known entities, such as what bacteria is going to exist, where they will exist, why they will exist, and what they 'will' accomplish. Creating less efficient microbial areas is simply not conducive to long-term system balance.

And, I could say that somewhat differently for those that prefer deep beds - if one is depending upon the influx of infauna to bring in the needed oxygen to the lower sandbed level to prevent anaerobic areas from forming, the predictability of infauna verses that of microbial processes remains highly questionable! Therefore, my position is to go with known parameters, and that would be the microbes themselves and not the 'possibility' that some worm or crustacean is going to create the right size burrow throughout the sandbed so as to prevent the majority of it from becoming anaerobic!

As for a color change below the two-inch level, that may be an indicator of hydrogen sulfide accumulating in the depths of your bed. A gray/blackish color would lead me to believe this possibility is a very real situation in your system. First, the occurrence of hydrogen sulfide in a deep bed is a normal happening. How much accumulates is the big question. And if present, should not be released into the bulk water. So don't stir the bed with any animals still in the aquarium. Plenum systems and shallow beds are less apt to develop serious hydrogen sulfide situations, simply because they contain more dissolved oxygen!

If you're interested in further understanding the microbial processes you can checkout what Martin Moe Jr. and Dr. Jean Jaubert have to say about my new book called 'The New Wave.' Visit my new website and check it out.

Hope this helps,

Bob